In the September issue of Nature Biotechnology, Stephanie Ruf and colleagues report the development of a plastid transformation system for tomato, Lycopersicon esculentum, and generation of the first edible transplastomic fruits (Nature Biotechnology 2001, 19:870-875).
Ruf et al. developed new transformation vectors for efficient delivery of foreign genes to chlororoplasts. They then created tomato plants expressing a selectable spectinomycin-resistance marker gene, aadA. Transformation procedures were modified by using low-light conditions and an extended selection phase, to optimize success. Ruf et al. found that the AadA protein was expressed at high levels in the tomato fruit, comprising about 0.5–1% of the total soluble cellular protein.
This technology will open up new possibilities for the development of plants expressing edible vaccines, antibodies ('plantibodies') and drugs.